I'm trying to get the following to work:
One CRT connected to a Matrox G550 AGP
One CRT connected to a NVidia GeForce4 MX 420 PCI
TV connected to the NVidia card.

I'd like to use the two CRTs as one Xinerama-like desktop and have one copy (of the part of the desktop displayed on the NVidia card) on the TV or, as an alternative, have the possibility to copy a windows content to the TV (or even Overlays like in Windows?).

I can set up each card seperately not using Xinerama and having only one CRT as my Desktop and either of the cards works, the NVidia even with TV out showing a copy of the desktop.
But as soon as I enable both video cards with or without Xinerama, X won't start up and the NVidia card will get locked showing vertical white stripes on black background (on both the CRT and the TV) while the Matrox card shows a black screen. One can't revert NVidias card to a normal state, even killing the X-Server or switching to the console doesn't help, although the system does not hang.
The X server doesn't produce any error message in its log files. When setting up two MetaModes for the NVidia card, one using just the CRT, the second enabling TV, X starts correctly. When I then try to switch the Mode to turn TV out on, X crashes with fatal error: "caught signal 11" (no other error messages appear), but before it's crashing, one can (for half a second or so) see the correct image on both the CRT and the TV.

I'm using Debian 3.0 on a Elitegroup K7S5A with Duron 800 processor with kernel 2.4.19. I'm using the newest drivers available from matrox and nvidia. I tried X 4.1 and 4.2 and I replaced the matrox card by another NVidia to make sure the failure is NVidia-related and is not some strange bug in the matrox drivers, which it isn't.

It is possible to use both cards with the XFree86 nv driver But this driver does not support (TV out as far as I know). Both video cards work with this driver. This is with a standard XFree86 installation from the ports dir.

To use the TV out i think i have to use the NVidia driver.
With the newly released nvidia driver which supports TV-out the error line i get when starting X is: Failed to initialize the NVdriver kernel module...............